FIGURE 1.

Dimeric cysteine substituted constructs. A, graphic depiction of the Kir channel inner cavity, with shaded clouds to indicate contrasting models for regions involved in high affinity polyamine block. B, construction of tandem-linked dimers of Kir6.2[C166S][N160D]. Assembled channels have negatively charged aspartates occupying the rectification controller position (N160D) in each subunit. The second subunit (back half, dark blue) includes a substituted cysteine. C, location of cysteine substitutions at pore-lining positions in the Kir inner cavity (numbering corresponds to Kir6.2; equivalent numbering for Kir2.1 is in parentheses).